Various imaging systems have been proposed that photographically capture images of a person's face for analysis of the health and aesthetic appearance of the skin. Different images, captured at different times or under different lighting conditions can be viewed and/or compared to one another to gain insight into the condition of the skin and its response to treatment. This may be done by inspecting the photographs to identify visual indicators of skin condition and to ascertain changes over time between photographs of the same type. When the skin is photographed under a particular type of illuminating light, e.g., produced by flashes or strobe lights emitting light of a particular range of wavelengths, the light intensity and wavelengths of the light can vary from one photograph to another due to variations in operation of the light source and/or any intervening filters. Imaging variations may also be due to variations in power supplied to the light source, a change in the operating condition of the light source, e.g., a burned-out filament, changes in filter transmissivity or color due to repeated exposure to high intensity light, a change in position of the light source, camera and/or filters, cracks in filters, dust, dirt or grease contamination of lights, lens and filters and/or changes in camera focus. Environmental lighting conditions can also lead to variations in illuminating light during an imaging session, e.g., due to the presence of varying environmental lighting, shadowing, obstructions to illumination or reflection of light from surfaces, etc. Variations in illuminating light and/or the light received by the camera, can result in variations in the digital images captured, which are not attributable to skin condition, thereby lessening the probative value of digital imaging analysis. Reliable and convenient apparatus and methods for testing the operation of various imaging system components to assure consistent operation are therefore desirable.